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Inventory of commonly used microwave passive components

Time：2023-07-27

Typically, RF devices can be divided into active and passive devices. Active devices include microwave components such as PA, LNA and RFIC that require an external power supply, and passive devices include passive filters, power dividers, and other microwave components that can work without an external power supply. Both active and passive devices are an indispensable part of RF circuits.

An RF isolator is a dual-port device that prevents RF energy from returning to its source. It is similar to a diode that only allows current to flow in one direction, or a check valve in a fluid flow system. Note that an RF isolator has absolutely nothing to do with current (ohmic) isolation used in non-RF signal and power supply designs, and it is not galvanically isolated.

Isolators: It is mainly used to protect other RF components from excessive signal reflection. For example, isolators are used in test applications to provide galvanic isolation between the device under test (DUT) and the sensitive signal source. This is done with some energy at the DUT reflected back to the source.

A circulator is a three-port device that controls the direction of signal flow (RF energy) in a circuit. Note that the isolator is also a ring with its third port terminated to match the load.

The most common application of circulators is that the transmitter and receiver share a single antenna, ensuring that high-power transmitted signals do not reach sensitive receiver input ports to prevent overload and possible damage. (The general term for this feature is a duplexer.) Ideally, the transmitted signal energy output will only reach the antenna port and will not be "seen" by the receiver, and the received signal will only reach the receiver.

Keywords： Inventory of commonly used microwave passive components